https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88784
--- Comment #9 from Qi Feng <ffengqi at gcc dot gnu.org> ---
And there's another problem. Take `x > y && x != 0 --> x > y' for
example, I would also like to do
x < y && y != 0 --> x < y
x != 0 && x > y --> x > y
y != 0 && x < y --> x < y
If the constant always comes in as the second operand is incorrect, these would
have to be doubled.
I tried to add :c to truth_andif, but got the `operation is not commutative'
error. I also tried to make truth_andif commutative by modifying genmatch.c,
but again, I don't know it well, afraid that I would break something.
The patterns I wrote looks like:
/* x > y && x != 0 --> x > y
Only for unsigned x and y. */
(simplify
(truth_andif:c (gt@2 @0 @1) (ne @0 integer_zerop))
(if (INTEGRAL_TYPE_P (TREE_TYPE(@0)) && TYPE_UNSIGNED (TREE_TYPE(@0))
&& INTEGRAL_TYPE_P (TREE_TYPE(@1)) && TYPE_UNSIGNED (TREE_TYPE(@1)))
@2))
I have to wrote 4 of this with minor modification for a single transformation.
If there's better way to do it, please do leave a comment.
